Radiation sensors

ABSTRACT

In accordance with at least one aspect of this disclosure, an ultraviolet radiation (UV) sensor includes a UV sensitive material and a first electrode and a second electrode connected in series through the UV sensitive material such that UV radiation can reach the UV sensitive material. The UV sensitive material can include at least one of zinc tin oxide, magnesium oxide, magnesium zinc oxide, or zinc oxide. The electrodes can be interdigitated comb electrodes.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 16/184,715 filed on Nov. 8, 2018, which is a divisional of U.S.patent application Ser. No. 15/217,955 filed on Jul. 22, 2016, whichclaims the benefit of priority to U.S. Provisional Application No.62/198,039, filed Jul. 28, 2015, which is incorporated herein byreference in its entirety.

BACKGROUND 1. Field

The present disclosure relates to sensors, more specifically toultraviolet sensors (e.g., for flame detection).

2. Description of Related Art

Traditional ultraviolet (UV) sensors can be used to detect flames, forexample, for use with flame and smoke detectors. Flames emit UVradiation which can be detected by a suitable sensor. However,traditional flame sensors are fragile, complicated, and expensive tomanufacture compared to traditional smoke detectors. Consequently,integration of smoke alarm and flame sensor in commercial andresidential applications has had limited success to date.

Such conventional methods and systems have generally been consideredsatisfactory for their intended purpose. However, there is still a needin the art for improved UV sensors. This can help to increase theadoption thereof in commercial and residential safety applications. Thepresent disclosure provides a solution for this need.

SUMMARY

In accordance with at least one aspect of this disclosure, anultraviolet radiation (UV) sensor includes a UV sensitive material and afirst electrode and a second electrode connected in series through theUV sensitive material such that UV radiation can reach the UV sensitivematerial.

The UV sensitive material can include at least one of tin oxide, zinctin oxide, magnesium oxide, magnesium zinc oxide, or zinc oxide. Theelectrodes can be interdigitated comb electrodes.

In certain embodiments, the UV sensitive material and the electrodes canbe coplanar. For example, the UV sensitive material can be disposed in aspace defined between the extensions of each comb electrode.

In certain embodiments, at least one of the electrodes and the UVsensitive material are at least partially transparent to UV radiation.For example, one or more of the electrodes can be UV-transparentelectrodes.

The UV sensitive material can be a separate layer from the electrodes.In certain embodiments, each electrode can be separated by a layer ofthe UV sensitive material. In certain embodiments, the sensor caninclude a first layer of the UV sensitive material, a second layerhaving a second layer comb electrode with second layer comb electrodeextensions, a third layer of UV sensitive material, and a fourth layerhaving a fourth layer comb electrode with fourth layer comb electrodeextensions. Any suitable additional layers or reduction of layers arecontemplated herein. For example, the sensor can further include a fifthlayer of the UV sensitive material such that the fifth layer has a combshape with fifth layer extensions that are less wide than the thirdlayer.

The second layer comb electrode extensions can be narrower than thefourth layer comb electrode extensions or any other suitable width. Incertain embodiments, the first layer can be a sheet and the third layerincludes a comb shape with third layer extensions.

The sensor can have a planar shape, a curved shape such as cylindricalor elliptical, or any other suitable linear or nonlinear shape. Forexample, the sensor can have a curved shaped (e.g., cylindrical). Incertain embodiments, the UV sensitive material can be disposed in aplanar spiral relationship. Alternatively, sensor electrodes may have aspiral relationship on a cylindrical, hemi-spherical or otherwisenon-planar concave or convex surface.

In certain embodiments, the sensor can include a conductive filmseparated from the electrodes by a dielectric for sensing capacitancebetween the conductive film and the electrodes. In certain embodiments,the dielectric can include the UV sensing material.

In accordance with at least one aspect of this disclosure, a method formanufacturing an ultraviolet (UV) sensor includes printing a UVsensitive material on or within a plurality of electrodes. In certainembodiments, the method can include printing the electrodes as describedherein.

The sensitive material can be deposited or printed in a space between aplurality of electrode extensions. The method can further includeforming the UV sensitive material to be coplanar with the electrodes toform a sensor layer. The method can include forming a plurality of thesensor layers one on top of another such that each sensor layer iselectrically separated by the UV sensitive material but UV radiation isallowed to pass through each layer to reach the UV sensitive material ineach sensor layer.

In accordance with at least one aspect of this disclosure, a radiationsensor includes a radiation sensitive material configured to besensitive to one or more wavelengths of radiation and a first electrodeand a second electrode connected in series through the radiationsensitive material such that radiation can reach the radiation sensitivematerial.

The radiation sensitive material can exhibit a greater absorbance ofultraviolet radiation than other adjacent radiation wavelength bands. Aradiation sensitive material absorbance can decrease above wavelengthsof about 200 nm. For example, the radiation sensitive materialabsorbance is at least about ten times higher at a portion of a band ofwavelengths between about 100 nm and about 400 nm versus a band ofwavelengths above 400 nm. In certain embodiments, the absorbance candrop about 80% at wavelengths higher than about 325 nm.

These and other features of the systems and methods of the subjectdisclosure will become more readily apparent to those skilled in the artfrom the following detailed description taken in conjunction with thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosureappertains will readily understand how to make and use the devices andmethods of the subject disclosure without undue experimentation,embodiments thereof will be described in detail herein below withreference to certain figures, wherein:

FIG. 1 is a plan view of an embodiment of a sensor in accordance withthis disclosure, showing UV sensitive material disposed between firstand second electrode extensions in a planar configuration;

FIG. 2A is a partially exploded perspective view of another embodimentof a sensor with multiple sensing layers in accordance with thisdisclosure;

FIG. 2B is an exploded plan view of each layer of the sensor of FIG. 2A;

FIG. 3 is an exploded plan view of each layer of another embodiment of asensor in accordance with this disclosure, shown having air gapsincreasing in size with each successive layer toward the outer surface;

FIG. 4 is a perspective view of another embodiment of a sensor inaccordance with this disclosure, shown having a curved shape;

FIG. 5 is a plan view of another embodiment of a sensor in accordancewith this disclosure, shown having a planar spiral shape;

FIG. 6 is partially exploded perspective view of another embodiment of asensor in accordance with this disclosure, showing a conductive layerdisposed in a capacitive relationship with the electrodes; and

FIG. 7 is a graph showing absorption of various embodiments of magnesiumzinc oxide semiconductors.

DETAILED DESCRIPTION

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectdisclosure. For purposes of explanation and illustration, and notlimitation, an illustrative view of an embodiment of a UV sensor inaccordance with the disclosure is shown in FIG. 1 and is designatedgenerally by reference character 100. Other embodiments and/or aspectsof this disclosure are shown in FIGS. 2A-7 The systems and methodsdescribed herein can be used to reduce the cost and improve theperformance of electromagnetic radiation sensors (e.g., UV sensors forflame detection).

In accordance with at least one aspect of this disclosure, anultraviolet radiation (UV) sensor 100 includes a UV sensitive material101, a first electrode 103, and a second electrode 105 connected inseries through the UV sensitive material 101 such that UV radiation canreach the UV sensitive material 101. As described herein, the UVsensitive material is configured to change a material property (e.g.,conductivity) as a function of UV radiation exposure.

In certain embodiments, the UV sensitive material 101 can include atleast one of tin oxide, zinc tin oxide, magnesium oxide, magnesium zincoxide, or zinc oxide. Any other suitable material is contemplated hereinfor use in the sensitive material 101, however, certain materials can beselected to minimize response to radiation other than UV (e.g., visiblelight, IR).

As shown, the electrodes 103, 105 can be interdigitated comb electrodes.This creates a space between each electrode extension 103 a, 105 a suchthat electrodes 103, 105 are not in direct electrical communication. Thespace between each electrode extension 103 a, 105 a can be selected tocreate a predetermined resistance (e.g., the smaller the spaces, thelarger the current flow will be between electrodes 103 a, 105 a). Anyother suitable shape of electrodes 103, 105 is contemplated herein.

In certain embodiments, as shown in FIG. 1, the UV sensitive material101 and the electrodes 103, 105 can be coplanar. For example, the UVsensitive material 101 can be disposed in the space defined between theelectrode extensions 103 a, 105 a of each electrode 103, 105. Such aplanar design can reduce the profile of the sensor and allow forwrapping, curving, and/or bending of the sensor 100 to any suitableshape.

The UV sensitive material 101 can be a separate layer from theelectrodes 103, 105. In certain embodiments, each electrode can beseparated by a layer of the UV sensitive material 101. For example,referring to FIGS. 2A and 2B, a sensor 200 can include plurality oflayers such that the sensor 200 has a stack or sandwich structure. Forexample, the sensor 200 includes a first layer 202 of the UV sensitivematerial 101, a second layer 204 having a second layer comb electrode203 with second layer comb electrode extensions 203 a, a third layer 206of UV sensitive material 101, and a fourth layer 208 having a fourthlayer comb electrode 205 a with fourth layer comb electrode extensions205 a. As shown, the comb electrode extensions 203 a, 205 a can beinterdigitated for each electrode, but any suitable electrode shape iscontemplated herein (e.g., a perimeter shape defining and opening in themiddle, a layer with a plurality of holes defined therethrough). Thelayers 202, 206 can have any suitable shape (e.g., interdigitatedmaterial extensions as shown).

In certain embodiments, as shown in FIG. 2B, a dielectric layer 222 canbe included at a bottom of the sensor 200. This dielectric layer 222 maybe reflective to enhance light collection by the sensor 200. In certainembodiments, the dielectric layer 222 can be made from the UV sensitivematerial 101, however, any other suitable dielectric material iscontemplated herein.

Referring to FIG. 3, an embodiment of a sensor 300 can include a taperedconstruction such that layers toward the front of the device allow moreUV radiation through to reach the back layers. For example, the fourthlayer 308 can include a fourth layer comb electrode 305 with secondlayer comb electrode extensions 305 a that are narrower than the secondlayer comb electrode extensions 303 a of a second layer comb electrode303 (e.g., to have larger spaces in the fourth layer 308 to allow moreradiation to reach the first, second, and third layers 302, 304, 306).However, it is contemplated that each electrode extension 303 a, 305 a(or UV sensitive material extension) can have any suitable width, shape,and/or other dimensions relative to other extensions.

In certain embodiments, the first layer 302 can be a sheet of UVsensitive material 101 and the third layer 306 includes a comb shapewith third layer extensions 307 a of the UV sensitive material 101. Asshown, the sensor 300 can further include a fifth layer 310 of the UVsensitive material 101. The fifth layer 310 can have a comb shape withfifth layer extensions 309 a that are less wide than the third layer306. As described above, any other suitable shape for each layer of UVsensitive material is contemplated herein.

While the embodiments disclosed herein show a discrete number of layers(e.g., four, five), any suitable additional layers or reduction oflayers is contemplated herein (e.g., two, three, ten). Further, certainstack or sandwich structures as shown in FIGS. 2 and 3 can allow forsensitivity through a side of the stack as well as through the frontand/or back.

In certain embodiments, at least one of the electrodes 103, 105, 303,305 and the UV sensitive material 101 can be at least partiallytransparent to UV radiation (e.g., to enhance passage of UV radiation tolayers in a stack). For example, one or more of the electrodes 103, 105,303, 305 as described hereinabove can be made of any suitabletransparent electrode material and/or in any suitable thickness to bepartially transparent. For example, if the layers are made sufficientlythin (e.g., about less than 10 nm), certain transition metal oxides maybe partially transparent. Any other suitable opacity is contemplatedherein.

As described above, the sensor 100 can have any suitable shape. Forexample, referring to FIG. 4, sensor 400 can have a curved shaped (e.g.,cylindrical, conical, tubular, non planar, hemispherical). For example,sensor layers may be directly deposited or printed onto a suitablenon-planar shape. Alternatively, a planar sensor (e.g., sensor 100) canbe deposited or printed on a flexible foil and can be wrapped to formcurved sensor 400. As shown, a solid piece of UV sensitive material 101can be wrapped with comb electrodes 403, 405 (e.g., electrodes 403, 405can be printed on to material 101). Any other suitable three-dimensionalshape (e.g., rectilinear shapes, spherical) is contemplated herein. Suchthree-dimensional shapes can allow UV radiation to reach the UVsensitive material 101 from multiple angles and thereby increase thefield of view without a focusing lens.

In another embodiment, referring to FIG. 5, the UV sensitive material101 can be disposed in a planar spiral relationship with the electrodes503, 505. Any other suitable planar arrangement is contemplated herein.As described above, the spiral electrodes 503, 505 and UV sensitivematerial 101 may be deposited or printed onto any suitable non-planarshape (e.g., cylindrical, conical, hemispherical, rectilinear shapes,spherical).

Referring to FIG. 6, the sensors as described above (e.g., sensor 100 asshown) can include a conductive film 601 separated from the electrodes103, 105 by a dielectric layer 622 for sensing capacitance between theconductive film 601 and the electrodes 103, 105. In certain embodiments,the dielectric can be the UV sensing material 101, but any othersuitable dielectric (e.g., air, UV sensitive material 101, or anotherinsulator) is contemplated herein. The conductive film 601 may be thesame material as the electrodes as described herein or any othersuitable conductive material.

Sensors and/or components thereof as described above can be manufacturedin any suitable manner. For example, sensors and/or components thereofas described above can be printed, sprayed, spin-coated, dipped, etched,or formed in any other suitable manner.

In accordance with at least one aspect of this disclosure, a method formanufacturing an ultraviolet (UV) sensor 100 includes deposition orprinting a UV sensitive material 101 on or within a plurality ofelectrodes 103, 105. In certain embodiments, the method can includedeposition or printing the electrodes 103, 105 having any suitableconstruction as described above.

For example, the UV sensitive material 101 can be deposited or printedin a space between a plurality of electrode extensions 103 a, 105 a. Themethod can further include forming the UV sensitive material 101 to becoplanar with the electrodes 103 a, 105 a to form a sensor layer. Themethod can include forming a plurality of the sensor layers one on topof another such that each sensor layer is electrically separated by theUV sensitive material 101 but UV radiation is allowed to pass througheach layer to reach the UV sensitive material 101 in each sensor layer.

Referring to FIG. 7, the UV sensitive material can exhibit a greaterabsorbance of ultraviolet radiation than other adjacent radiationwavelength bands (e.g., visible wavelengths, x-ray wavelengths). Asshown in FIG. 7, a UV sensitive material absorbance can decrease abovewavelengths of about 200 nm for various magnesium zinc oxidecompositions. For example, the UV sensitive material absorbance can beat least about ten times higher at a portion of a band of wavelengthsbetween about 100 nm and about 400 nm versus a band of wavelengths above400 nm. In certain embodiments, the absorbance can drop about 80% atwavelengths higher than about 325 nm for certain zinc tin oxidecompounds. (See “Caihong Liu, Haiyan Chen, Zheng Ren, Sameh Dardona,Martin Piech, Haiyong Gao and Pu-Xian Gao, Controlled Synthesis andStructure Tunability of Photocatalytically Active Mesoporous Metal-basedStannate Nanostructures, Appl. Surf. Sci., 2014, 296, 53-60.”).

While the embodiments hereinabove are described as being configured forUV radiation sensing, it is contemplated that certain embodiments ofsensors can be configured (e.g., via suitable material selection of thesensitive material) to be sensitive to any other wavelength of radiation(e.g., visible, infrared).

The methods and systems of the present disclosure, as described aboveand shown in the drawings, provide for radiation sensors with superiorproperties including improved performance and reduced cost. While theapparatus and methods of the subject disclosure have been shown anddescribed with reference to embodiments, those skilled in the art willreadily appreciate that changes and/or modifications may be made theretowithout departing from the spirit and scope of the subject disclosure.

What is claimed is:
 1. A method for manufacturing a radiation sensor,comprising: depositing or printing a radiation sensitive material on orwithin a plurality of electrodes, wherein the electrodes areinterdigitated and the radiation sensitive material is deposited orprinted in a space between a plurality of electrode extensions, whereindepositing or printing the radiation sensitive material includes formingthe radiation sensitive material to be coplanar with the electrodes toform a sensor layer.
 2. The method of claim 1, further comprisingdepositing or printing the electrodes.
 3. The method of claim 1, furthercomprising forming a plurality of the sensor layers one on top ofanother such that each sensor layer is electrically separated by theradiation sensitive material but radiation is allowed to pass througheach layer to reach the radiation sensitive material in each sensorlayer.